Effects of antimony-doped on yttrium-site of YBCO-123 using density functional theory via first principle study / Nuraini Najihah Zulkifli

Antimony-doped on Yttrium site of YBa2Cu30⸹) was examined using Density
Functional Theory via First Principle Study. The effect of Sb doping on YBCO123
has been studied via computational simulation to determine the structural
properties and electronic properties. From the simulation of Material Studio
CASTEP software through Density Functional Theory, the optimized crystal
structure has been developed. Generally, the lattice parameters results shows that
the doped samples did not differ much from the standard sample for x = 0.0625
until x = 0.1875 except for Sb doped of x = 0.2500 until x = 0.5000 that displayed
shortening of a-parameter and b-parameter while elongating c-parameter. The
sample has a crystal structure of orthorhombic as they have different lattice
parameter where a ≠ b ≠ c. For the electronic band structure, the addition of Sb
(III) have a negligible effect on the main crystalline structure of the YBCO-123
specially at low concentration from doping x = 0.0625 to x = 0.2500 but start to be
unstable specially at high concentration from doping x = 0.3125 to x = 0.5000 The
results were analysed that the states of existing holes in Y1-xSbxBa2Cu30⸹ are
obtained by investigating the states above the Fermi level, not below it. The
density of states graph showed that the electron near and below Fermi level was
highly concentrated which are involved in the formation of superconducting
properties. The charge density for one electron per unit cell above Fermi level
shows that holes exist mainly in the CU-02 plane. The energy shifts observed via
total and partial density of state at Cu 3d and 0 2p orbital towards the Fermi level
with different concentration of dopant confirms the superconducting ability and its
electronic behaviour.